The present invention relates to a variable magnification electrostatic copying machine comprising means for automatically adjusting the magnification ratio depending on the size of an original document and a copy sheet.
In conventional variable magnification copying the sizes of original documents and copy sheets are compared and a manual magnification control set by the operator. For example, if an A3 size document is to be reproduced on an A4 size copy sheet, the magnification is set at about 70% to reduce the size of the image on the copy sheet relative to the size of the image on the document. Conversely, if a B5 size document is to be reproduced on an A4 size copy sheet, the magnification is set at about 115% to enlarge the size of the image on the copy sheet relative to the size of the image on the document. This manual operation of setting the magnification is a nuisance and results in wasted copies since inexperienced operators often set the wrong magnification and even experienced operators often forget to ensure that the magnification setting is correct.
Another drawback in the art developed heretofore is that on some documents the image is parallel to the long side of the document and on other documents the image is parallel to the short side of the document. Where the magnification is set depending only on the sizes of the documents and copy sheets, the result will be that the copies look just like the originals.
This is not always desirable since where copies of documents are filed or bound together to form a book or report, some of the images on the copies will be vertical whereas others will be horizontal depending on the orientation of the images on the original documents. This means that the book or report must be rotated by 90.degree. to read a horizontal page after reading a vertical page and vice-versa. The book or report is much easier to read if all the images on the pages are oriented in the same direction.